As of right now we still don't know what Steven Spielberg is going to do for his next directing project, but it looks like he's lining up another possibility. According to Deadline, he is looking to take on a film called Montezuma, which will tell "an epic tale of the kinship and ultimately the bloody collision between Montezuma and Cortez as the latter led the Spanish infiltration into Mexico."
The site goes on to say that Javier Bardem is up for the role of the Spanish explorer Hernando Cortez. Apparently the film was inspired by a 50-year old script written by Dalton Trumbo, which is being rewritten by Steve Zaillian, who also worked with Spielberg on Schindler’s List.
Word is the project could be retitled Cortez, because the viewpoint will be from the character to be played by Bardem. The site also points out that the project is "considered one of the great unmade scripts in moviedom, [and] has an illustrious history." It was written for actor/producer Kirk Douglas. Trumbo worked with Douglas on classics such as Spartacus and Lonely Are the Brave. The original 1965 draft was supposed to be directed by Martin Ritt and star Douglas, but it obviously never happened.
This seems like it would make a great project for Spielberg! I'd love to see him take it on. There's no word on if it will be his next project, or if it will happen later on down the road. He was recently attached to direct Robopocalypse and American Sniper, but he's not making either of those now. Maybe one day he'll get around to Robopocalypse, but I don't think it will happen anytime soon.